In a hot-strip mill it is standard practice to square the edges of the strip being produced by means of an edge-roller assembly having a pair of edge rollers rotatable about parallel vertical axis that flank the horizontal plane of the strip adjacent a standard roller stand having a pair of vertically offset horizontal rollers rotatable about horizontal axes. The edge rollers engage the edge of the strip being produced to square it.
Normally such edge rollers are journaled in support blocks displaceable horizontally relative to heavy-duty guides which are frequently secured to the stands of the adjacent roll assembly. Each of the support blocks is associated with a respective heavy-duty spindle that is threaded in a nut carried fixedly on the guide and that axially bears against the respective support block. An appropriate drive is provided for rotating this spindle, screwing it in the nut, and thereby displacing the respective roller and support block relative to the guide. Normally such a spindle has a screw thread which is made as flat as possible consonant with a usable adjustment speed. The horizontal spacing between the two edge rollers is normally set before the workpiece engages them.
In a reversing-strip mill it would, however, be advantageous to be able to reset the spacing between the edge rollers between consecutive passes of the workpiece. Such resetting could compensate for the normal thermal contraction of the workpiece as it cools.
The above-described spindle arrangement cannot be used to reset the edge rollers while they engage the workpiece. Dimensioning the spindle large enough and the thread flat enough to be able to exert the necessary large amount of force on the workpiece while it is engaged between the edge rollers would create an impractical bulky assembly. In addition such an assembly would inherently have an extremely slow adjustment speed so that it would take quite some time to bring the edge rollers to the desired spacing when roller spacing is changed.
Accordingly it has been standard practice to simply set the edge rollers at a spacing which is a compromise between the spacing appropriate for the first pass and the spacing appropriate for the second pass. The result is a workpiece whose edges are not perfectly squared, and where the edges are frequently subjected to excessive deformation on the first pass.